This invention relates to wheel assemblies and particularly to guide rollers that travel along guide rails or tracks such as in the case of segmented overhead doors and overhead trolley conveyors. More particularly, the invention relates to a wheel-assembly having a flexible design that permits variations in the length of the supporting shaft and size of roller, dimensions while using many of the same basic components.
Various types of wheel-assemblies have been used in connection with segmented overhead doors such as for garages and various types of cargo trucks. These assemblies usually have a roller that travels on a guide rail or track.
Problems have arisen due, for example, to vibration and irregular stresses that are induced during opening and closing of a segmented door. Failures can also occur due to excessive end thrusts against the bearings. Furthermore, it is difficult to find an effective means for journaling the wheel assembly in brackets located on the particular structure to be moved and guided. Another problem is the formation of rust that can occur due to exposure to weather conditions. Still another problem is that of providing lubrication for the bearing surfaces.
The wheel assembly of the present invention resolves many of the difficulties described above and affords other features and advantages heretofore not obtainable.
It is among the objects of invention to provide a novel wheel assembly of improved reliability and improved resistance to corrosion and wear due to conditions of use. Still another object is to provide a wheel assembly of simplified design that lends itself to automated assembly. These and other objects and advantages are achieved with the unique roller assembly of the present invention which is especially adapted for use in connection with segmented doors.
The assembly includes as one of its primary components, a unique adaptor having an inner end portion that is tubular and provided with an axial socket, and a cylindrical outer end portion that provides a bearing surface and that has a diameter smaller than that of the inner cylindrical portion. The two portions thus define a retainer shoulder between them. A roller formed of porous sintered metal impregnated with a lubricant is mounted on the outer bearing portion of the adaptor and is located adjacent to the shoulder. A spring retainer is forced onto the projecting end of the cylindrical end portion so that the roller is retained between the shoulder and the spring retainer.
An elongated shaft is forced into the socket formed in the inner end portion of the adaptor to complete the assembly. The socket is provided with axially extending ribs that grip the end of the shaft to assure that the assembly is tightly retained on the shaft with an interference fit.
In accordance with one aspect of the invention, washers or spacers formed of polyethylene are positioned on opposite sides of the roller in engagement with the shoulder and the retainer spring respectively. Also, the bore in the roller is provided with a plurality of axially extending grooves that serve to collect any debris that may get into the assembly.